Using microcannulation procedures, we propose (1) to investigate under in vivo conditions the mechanisms whereby anterior and posterior pituitary hormones are secreted into pituitary stalk blood resulting in super-high concentrations in stalk plasma of LH, FSH, TSH, prolactin, ACTH, alpha-MSH, and vasopressin; (2) to determine the role of posterior pituitary hormones in the control of anterior pituitary hormone secretion; (3) to investigate the role of thyroid hormones, gonadal steroids, and adrenal steroids in the secretion of pituitary hormones into stalk blood; (4) to investigate the significance of retrograde blood flow in the pituitary stalk in the delivery of pituitary hormones to, and their transport across, the median eminence and hence to the brain; (5) to determine the mechanisms involved in the hypothalamic secretion of LHRH, TRH, and dopamine into hypothalamic-hypophysial portal blood. Using in vitro conditions, we propose (1) to characterize the subcellular compartmentalization of LHRH, TRH, and alpha-MSH in synaptosome-like particles, hereafter called synaptosomes, prepared from hypothalamic homogenates; (2) to investigate the mechanisms involved in the storage and release of LHRH, TRH, and alpha-MSH from synaptosomes; (3) to test the hypothesis that Ca 2 ion in the presence of depolarizing concentrations of K ion causes TRH, LHRH, and alpha-MSH release from synaptosomes by activating guanylate cyclase and/or adenylate cyclase, thereby forming cGMP and/or cAMP; (4) to investigate the role of synaptosomal microtubules, tubulin, and microfilaments in the exocytosis of TRH, LHRH, and alpha-MSH; (5) to investigate the role of prostaglandins, viz., PGE2 and PGF2 alpha, prostaglandin precursors, and phospholipids enriched with arachidonic acid and lysophospholipids in the release of TRH, LHRH, and alpha-MSH from synaptosomes.